The industrial-robots having a workpiece handling robot and a tool handling robot provided with a tool, such as a machining tool, a welding torch or a welding gun etc., are generally controlled by a method of teaching playback so as to move both robots at the same time in real processing operations.
The teaching operations for the robots have to be performed before real processing operations. Both robots are subjected to sole-acting manual operation.
Referring to FIG. 24(a) of the prior art, the desired positioning for each robot are first independently achieved by means of separate movement of workpiece 1m on the workpiece handling robot 1 from the movement of tool 2n on the tool handling robot 2. The point A in the "position and attitude", which are established by the above-mentioned independent movement, is taught as a teaching point of the first position. This means that the data of "position and attitude" of tool 2n against workpiece 1m at the point A and the data of "joint variables" of workpiece handling robot 1 are memorized in a computer.
Thereafter, tool 2n and workpiece 1m have to be moved according to commands of an operator in order to obtain the second position. When the workpiece 1m is moved by means of movement of workpiece handling robot only as shown by a broken line, after the teaching point A of the first position, the workpiece 1m often contacts or collides with the tool 2n. Therefore, it is necessary to avoid the interference of workpiece 1m and tool 2n with each other.
An operator needs to command tool 2n to retire from workpiece 1m as shown in FIG. 24(b), after teaching point A at the first position.
Next, the workpiece 1m is moved in the direction of an arrow 1p by moving the workpiece handling robot 1 as shown in FIG. 24(c) in order to obtain a desired position for a next teaching point B. As shown in FIG. 24(d), the point B is taught at the second position which is established by returning tool 2n to workpiece 1m through the movement of tool handling robot 2.
It is very inconvenient to retire the tool from the workpiece in the middle of teaching operations. Many teaching points forces an increase of in the number of times for retiring the tool from the workpiece. Because it takes a lot of time to retire the tool and to return the tool the teaching time is, on the whole, prolonged.
Furthermore, an operator often loses sight of the desired next teaching point on the workpiece when the distance between a teaching point and a next one is short or when an arrangement of a series of teaching points is complicated.
The first objects of this invention is to enable a tool on tool handling robot the movement of workpiece on workpiece handling robot by means of co-acting with each other when an operator teaches both of robots by the manual operations.
The second object is to exactly realize and maintain previous position and attitude of the tool against the workpiece without retiring the tool from the workpiece one by one during the teaching operations.
The third object is to present a teaching control device for simplified manual teaching operations in an industrial robots-system where teaching operations can be rapidly performed by means of accurately subjecting the tool to movement of the workpiece.